Extension Blocklisting:Code Design

Simple blacklisting for Firefox 1.5

Update model

• Download a blacklist file on a timer (86400 default)
• If items are newly blacklisted or unblacklisted, adjust the datasource appropriately and prompt to restart.
• The blacklist file will be placed in the profile-dir.
• Blacklist is _replaced_ on each update, not merged or otherwise combined.

Blacklist syntax

• The blacklist file has a flexible xml syntax that will use default values for values that are not specified. All Extension Manager items must be children of emItems in order to ease the use of this file for additional blacklist items such as plugins that are not managed by the Extension Manager.

Examples:

<blacklist xmlns="http://www.mozilla.org/2006/blacklist">
  <emItems>
    <emItem id="item_1@domain">
      <versionRange minVersion="1.0" maxVersion="2.0.*">
        <targetApplication id="{ec8030f7-c20a-464f-9b0e-13a3a9e97384}">
          <versionRange minVersion="1.5" maxVersion="1.5.*"/>
          <versionRange minVersion="1.7" maxVersion="1.7.*"/>
        </targetApplication>
        <targetApplication id="toolkit@mozilla.org">
          <versionRange minVersion="1.8" maxVersion="1.8.*"/>
        </targetApplication>
      </versionRange>
      <versionRange minVersion="3.0" maxVersion="3.0.*">
        <targetApplication id="{ec8030f7-c20a-464f-9b0e-13a3a9e97384}">
          <versionRange minVersion="1.5" maxVersion="1.5.*"/>
        </targetApplication>
        <targetApplication id="toolkit@mozilla.org">
          <versionRange minVersion="1.8" maxVersion="1.8.*"/>
        </targetApplication>
      </versionRange>
    </emItem>
    <emItem id="item_2@domain">
      <versionRange minVersion="3.1" maxVersion="4.*"/>
    </emItem>
    <emItem id="item_3@domain">
      <versionRange>
        <targetApplication id="{ec8030f7-c20a-464f-9b0e-13a3a9e97384}">
          <versionRange minVersion="1.5" maxVersion="1.5.*"/>
        </targetApplication>
      </versionRange>
    </emItem>
    <emItem id="item_4@domain">
      <versionRange>
        <targetApplication>
          <versionRange minVersion="1.5" maxVersion="1.5.*"/>
        </targetApplication>
      </versionRange>
    <emItem id="item_5@domain"/>
  </emItems>
</blacklist>

Examples Explained:

• The item_1@domain Extension Manager item will be blacklisted if a version between 1.0 and 2.0.* (e.g. less than 2.1) is installed and the Firefox (e.g. id equal to {ec8030f7-c20a-464f-9b0e-13a3a9e97384}) version is between 1.5 and 1.5.* (e.g. less than 1.6), the Firefox version is between 1.7 and 1.7.* (e.g. less than 1.8), or the Toolkit version is between 1.8 and 1.8.* (e.g. less than 1.9). Also, the item_1@domain Extension Manager item will be blacklisted if a version between 3.0 and 3.0.* (e.g. less than 3.1) is installed and the Firefox (e.g. id equal to {ec8030f7-c20a-464f-9b0e-13a3a9e97384}) version is between 1.5 and 1.5.* (e.g. less than 1.6) or the Toolkit version is between 1.8 and 1.8.* (e.g. less than 1.9).
• The item_2@domain Extension Manager item will be blacklisted if a version between 3.1 and 4.* (e.g. less than 5) is installed for all version of the current application.
• All version of the item_3@domain Extension Manager item will be blacklisted if the Firefox (e.g. id equal to {ec8030f7-c20a-464f-9b0e-13a3a9e97384}) version is between 1.5 and 1.5.* (e.g. less than 1.6).
• All versions of the item_4@domain Extension Manager item will be blacklisted if the current application version is between 1.5 and 1.5.* (e.g. less than 1.6).
• All versions of the item_5@domain Extension Manager item will be blacklisted for all version of the current application.

As can be seen it is possible to blacklist all version of an extension for all versions of an application as well as any combination of application id's along with version ranges for both the extension id and application id. Also, by not specifying a value and instead using the default value it is possible to lessen the size of the blacklist xml file. This is possible by using the following defaults:

• minVersion = 0
• maxVersion = *
• targetApplication id = current application id

At first glance it may seem more appropriate to use a plain text file and parse delimited values. The draw back of this method are that extension id's and application id's would have to be specified multiple times whereas with this format we are able to specify each extension id one time only and each application id for an extension id one time only.

If an extension's metadata matches all of the conditions it will be blacklisted and no further checking for that extension will be performed. This allows handling of overlapping ranges though there has been no use case for supporting overlapping ranges.

Support for a targetApplication id of toolkit@mozilla.org has been added since this will be necessary after Bug 299716 is fixed.

We will be using individual blacklist files for each application in order to not penalize one application that has few or no blacklist items with the blacklist for an application that contains numerous blacklisted items.